


Down the Hatch

by ChlorineTriflouride



Category: Phineas and Ferb
Genre: Aged-Up Character(s), Alternate Universe - Canon Divergence, F/M, Sex, Sibling Incest, Size Difference, Vibrators, Vore
Language: English
Status: Completed
Published: 2018-07-28
Updated: 2018-07-28
Packaged: 2019-06-17 20:24:57
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,047
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15469344
Author URL: https://archiveofourown.org/users/ChlorineTriflouride/pseuds/ChlorineTriflouride
Summary: Two hundred feet of height difference is alotfor lovers to deal with, and intimacy is no exception. But... one way or another, they've managed for the past two decades, and they'll manage now.





	Down the Hatch

**Author's Note:**

  * Inspired by [Rise and Shine](https://archiveofourown.org/works/15461367) by [Toxic_Waste](https://archiveofourown.org/users/Toxic_Waste/pseuds/Toxic_Waste). 



Rebreathers were amazing technology, especially the advanced one Phineas made for himself, the little one he could insert into his throat and then simply breathe the same breath of air for ever and ever, the carbon dioxide being ripped into perfectly fresh oxygen for his lungs and the excess carbon being dropped into his stomach for eventual disposal out the tail end of his digestive system.

They could, in theory, enable infinite underwater breathing time, with only a single intake of breath, or allow one to walk freely into outer space without a worry or a care. The other thing they could do, though, was what he was most interested in at the moment.

He patted the tiny rubber pack strapped to his upper arm, the length of ultra-strong carbon-fiber-steel reinforced rope coiled over his shoulder, and passed the remote control between his hands, and grinning in anticipation, looking up at his sister as patiently as he knew how. He shifted his weight back and forth between his feet, the skin of her upper legs warm and pliable beneath his feet as he waited.

Candace swallowed the last gulp of the chunky antiacid in her gargantuan cup, and set it down on the floor next to the bed with a such a tremendous impact that Phineas almost fell down. Then again, he wasn’t standing very steadily or firmly anyway.

She grinned down at him, her hand coming up and settling down close by. “Are you that ready, then?”

“I’m the one who’s been waiting, you know,” he replied.

Candace rolled her eyes and leaned back into the pillows – far enough back that her stomach and chest became a walkable surface, though not quite completely prone.

Phineas grinned and set off up the slope as she watched. It was a bit unstable beneath his feet at first, though once he managed to get past the forty or so feet of her stomach and onto her breastbone, the sturdiness of her bones just inches beneath the surface of her skin was more than enough for him to be able to walk as confidently as he desired.

Which was quite confidently – and in a few more paces, he stopped – still a good distance from her shoulders, standing squarely between her breasts. Candace raised her eyebrows, but said nothing as he turned and clambered up the height of one. Though they were small from a proportional point view – as compared to the rest of her body – that ultimately didn’t change the fact that each one was fifteen feet across and rose nearly four feet from the surface of her chest, which more than any other person on the face of the planet could ever hope to achieve.

The wide disc of her areola was there, and he knelt down, wrapping his hands around her nipple and squeezing as firmly as he was able.

A mild tremor reverberated through the ground beneath him – Candace flinched slightly. He would never be big enough to really _fondle_  her, per se, but there were always ways around everything. Uncoiling the rope from around his waist, he wrapped it around her nipple and knotted it securely. With a firm grip on the cord, and bracing his feet into her skin, he gave it a firm tug.

The ground shifted again, and he smiled. “Do you like that?”

“You know I do,” she answered, her voice booming even louder from being so very, very close.

“I do, yes.” He redoubled his grip on the rope and pulled as hard as could. Letting it through his hands slowly, he walked backwards, crossing her chest to the _other_ breast, the other nipple. The other end of the rope, too, was knotted firmly around this one, squeezing the soft surface tightly, leaving only very little slack between.

Taking the length of the stretched rope with both hands, he pulled back with all his strength, eating the slack in an instant, and the ground vibrated under him as Candace shivered softly. Nearly a hundred feet below, her hand patted about on the bed next to her, her fingers eventually settling over the multi-ton vibrator lying there. She picked it up and slid it between her legs.

The motion did not escape Phineas’ notice, and keeping the rope tugging at her nipples taut, he dug his heels into her skin for traction and shifted to a one-handed grip on the rope - reaching for the remote control strapped to his upper arm with the other. Grinning, he depressed the button, and another tremor jostled through the ground beneath him. Candace sighed.

Phineas tugged at her nipples, first one, then the other – alternating, randomly, in no pattern whatsoever, really. He let the vibrator run for a moment or two. Candace moaned softly, and he abruptly cut it off, putting it away and walking hand-over-hand on the rope towards her leftmost nipple.  The knot wasn’t slipping, and it was redder from the squeezing, even as he let it go momentarily.

Pulling the rope as taut as he could, he wrapped the extra length around and around her nipple, and knotted it again, doubly firmly. These knots would have to last – and the rope was stretched rigid between her hardened nipples, unwaveringly pulling them, not giving an inch.

Phineas patted the smooth surface of the nipple at his feet, then crouched and jumped, coming down squarely atop it. Candace flinched, and he toppled off sideways onto her breast, and would have rolled farther down the slope had he not grabbed ahold of the rope suspended there. It sagged a bit more under his weight, tugging downwards, and Candace’s face turned into a crooked sort of smile.

He pulled himself back to his feet, producing the remote control again, speaking as he depressed the button on it. “You like that, sis?” He stepped up onto her nipple again, bouncing his weight up and down, and she nodded.

“Just c’mere, Phin. I think it’s about time for this part, too.” Her free hand suddenly hovered over him, the fingers curling around the nape of his neck and beneath his arms, plucking him instantly away from her breasts and lifting him effortlessly up over her face.

He squirmed against her fingers, but each one was unwavering, warm and soft and yet eternally unyielding, pinning his arms against his sides and his legs together as she clutched his body in her fist. Her mouth gaped open like a yawning chasm, and her immense tongue lolled out.

It reached for him, the wide, fleshy mass brushing against the top of his head, soaking his hair in copious amounts of saliva that oozed down over him. She opened her palm, and he lay still as it passed over his body, sopping up the thin layer of sweat that had collected on him as he'd climbed up and down her body, replacing it with the warmer, slightly stickier liquid. He shivered himself, now, as it curled between his legs, leaving no crevice of his body untouched, the pitted surface of the taste buds scraping over his skin, the saliva running over him making it impossible to do more than flail helplessly about at the lack of traction.

She turned her palm over in a single motion, and it was her tongue that was beneath him now. He turned up the dial on the remote control moments before the device succumbed to the liquid coating every inch of his bare skin, shorting out and falling out of his hand and down to the distant ground below as her tongue retreated into her mouth and it closed up behind him.

It was dark and warm, only a faint current of air from the back of her throat, saliva dripping down from the roof and coating every surface, filling the cavity. Her tongue bore him up, pressing him against her palate, and he wriggled against the muscle, which only redoubled its strength, holding him in place as gallons of saliva coursed past him, down towards the gaping entrance to her throat just behind. There was no moving there – he grew hard as the fleshy mass shifted beneath him, swelling and shrinking, ticklingly caressing every part of him at once, almost enveloping him as it pinned him in place for her to suck on his body.

A moan shook through her mouth, the vibrations rippling through his limbs and he moaned in kind – the saliva sloshed into his mouth and throat, tasteless and warm, seeming to permeate through him with it’s warmth as it did so, her tongue outside rapidly curling and uncurling around his body, each pass over driving him farther towards climax – his back pressed firmly into her unmoving palate.

The constant flow of saliva began shrinking, and Candace moaned around him again, pressing the vibrator more against herself, hooking one finger around the rope her brother had tied to her nipples, tugging much harder at it than he could ever hope to do. The rope strained, but didn’t quite break, and her back arched against the pillows.

Phineas wiggled about in her mouth, going, going, getting nowhere, struggling against her tongue. He tried to moan again, voicelessly, his mouth filled with saliva and his face pressed against the fleshy mass. He could take it no longer and climaxed – for a moment or two, she could taste his ejaculate mingling into her mouth, mixing with the hundreds of gallons of her spit and washing down her throat. She pressed the vibrator harder against herself, and the saliva ran totally dry for a brief moment.

Her palate lifted, and Phineas trembled in anticipation as her tongue arched back, shoving him towards her throat. It gaped wide, and there was only frictionless flesh to brace against in the pitch darkness. Her tongue roughly pushed him back past her molars – muscles larger than his entire person contracted powerfully around him, shoving him down. The walls of her throat crashed around him, kneading his body, pinning him in their vice-like grip.

Candace swallowed, the lump in her throat passing down, and she opened her mouth, moaning aloud as she came to orgasm, her heartbeat pounding loudly as her brother was crushed down her esophagus, bit by bit. She gasped, her other hand jerking against the rope on her nipples, snapping it effortlessly like a piece of thread as she leaned back into the pillows.

Phineas couldn’t move, could scarcely breathe, the walls of her throat clamped tight around him, squeezing from every side, rhythmic contractions of muscle kneading up and down every square inch of his body, sliding him down the cramped tube. His feet were the first to dangle free, and then his legs, and he was suddenly freed, dropping down into an open cavity, landing with a splash in a thick, chunky liquid in the darkness.

His hand instinctively flew to the rubber packet strapped to his upper arm, pulling a tiny string attached to it, and the insta-wetsuit popped out, coating his skin in an instant, long before the temporarily-weakened acids in her stomach had managed any harm.

It was dark, and the walls grumbled and gurgled around him, and her gradually slowing heartbeat thudded powerfully just a short distance away. He floated to the surface of the acid, floating easily in the thick soup as it sloshed back and forth, and breathed heavily into the enclosed space.

He grinned – though he knew well enough that it wasn’t over quite over, either. A lull, as Candace basked in the afterglow of her climax, and her body came down from the high. Her digestive system would restart, and her intestines and their countless villi still waited for him in the darkness.

For now, though, as he floated in the acidic pool in the pitch dark, very much inside his sister, he was satisfied. Candace curled into a vaguely fetal position around her stomach, her face etched in a satisfied smile that somehow still managed to convey at least a hint of the overwhelming protectiveness that had always been a hallmark of her relationship with her brother.

It would be a good few hours until she _saw_ him again, but that was okay. He would be right there, and they - the both of them - would be just fine.


End file.
